Clinical Manifestations and Treatment of Hashimoto's Encephalopathy

Hashimoto’s encephalopathy (HE), or corticosteroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT), is a rare neuroinflammatory syndrome of the central nervous system characterized by a predominance in females and a subacute onset of heterogeneous neuropsychiatric manifestations, such as cognitive decline, delirium, catatonia, epileptic seizures, and stroke-like episodes. Its pathogenesis remains unclear, with antithyroid antibodies (anti-TPO and anti-Tg) acting as markers of systemic immune dysregulation rather than direct etiological agents. The objective of this study was to synthesize and critically analyze the clinical presentations, differential diagnosis, and advances in the therapeutic management of EH. This is a narrative literature review; the search was conducted in the PubMed database using the MeSH descriptors “Hashimoto’s Encephalopathy” and “Therapeutics”, encompassing articles published between 2021 and 2026 in Portuguese and English. The diagnosis of EH is based on the rigorous exclusion of alternative etiologies and on the criteria established by Graus et al. (2016), combining encephalic dysfunction, antithyroid seropositivity, negativity for neuronal autoantibodies, and nonspecific abnormalities in the cerebrospinal fluid and electroencephalogram. Magnetic resonance imaging (MRI) is normal in up to half of cases; of particular note are the migratory pattern of lesions and the superiority of 18F-FDG PET. The occurrence of drug-resistant epileptic seizures signals the transition to autoimmune encephalitis-associated epilepsy (AEAE), resulting from T-cell-mediated focal neuronal damage. Pulse therapy with methylprednisolone constitutes the initial therapeutic pillar; however, an incomplete response in approximately two-thirds of patients requires escalation to intravenous immunoglobulin, azathioprine, or rituximab, in combination with neurorehabilitation. It is concluded that an early multidisciplinary approach and individualized tapering of immunosuppression are critical for limiting neurostructural damage, preventing relapses, and optimizing the functional prognosis.